Chain mountable gripper

ABSTRACT

The invention disclosed is directed to a gripper for gripping an advancing web between a jaw face of the gripper and a jaw face presented by a link in an endless chain including pins pivotally interconnecting adjacent links, at least selected ones of the pins each having a hole therethrough. The gripper comprises a generally U-shaped portion comprising first and second arms connected by a bridging member, the first arm being receivable in one of the holes, the second arm having a jaw face adapted to cooperate with the jaw of a link, and the mounting member. Closing, gripping, and opening are effected simply by the cycling travel of the chain through arcuate and linear modes. Also disclosed is a chain assembly including the gripper.

United States Patent 1191 Reid [52] US. Cl. 26/61 B; 26/62 B; 226/173; 198/180; 271/205 [51] Int. Cl. D066 3/02 [58] Field of Search 198/180, 179; 271/204, 271/206, 277, 205; 226/173; 26/52, 57, 61 B,

[56] References Cited UNITED STATES PATENTS 1,920,715 8/1933 Sager 271/204 1451 May 6,1975

Primary ExaminerEvon C. Blunk Assistant Examiner-James M. Slattery Attorney, Agent, or Firm-John J. Toney; William D. Lee, Jr.

[5 7 ABSTRACT The invention disclosed is directed to a gripper for gripping an advancing web between a jaw face of the gripper and a jaw face presented by a link in an endless chain including pins pivotally interconnecting adjacent links, at least selected ones of the pins each having a hole therethrough. The gripper comprises a generally U-shaped portion comprising first and second arms connected by a bridging member, the first arm being receivable in one of the holes, the second arm having a jaw face adapted to cooperate with the jaw of a link, and the mounting member. Closing, gripping, and opening are effected simply by the cycling travel of the chain through arcuate and linear modes. Also disclosed is a chain assembly including the gripper.

12 Claims, 9 Drawing Figures W IENTED HAY 61975 SHEET 10F 2 PATENTEDHAY 6 m5 SHEET 2 BF 2 CHAIN MOUNTABLE GRIPPER This invention relates to a gripper for gripping an advancing web of sheet material and to an assembly which includes the gripper as a component thereof.

The prior art is replete with devices for gripping advancing webs of sheet material. For example, numerous clips and chain-clip assemblies are known in the tentering art. In conventional tenter dryers, a continuous length of web material is conveyed through the dryer by tenter elements, either tenter clips or tenter pins, which engage the lateral marginal portions of the web and slide longitudinally through the dryer on chain rails along the opposite sides of the dryer housing. The two chain rails are mounted for transverse adjustment within predetermined limits so that they may be disposed parallel to one another or may be adjusted to converge or diverge at various angles, depending on the character of the web material being dryed.

When orienting synthetic films, the tentering machine is set to resist film shrinkage and to stretch the web laterally. When tentering synthetic films, the web is normally held by tenter clips having a lower fixed jaw on a body slidable on the rail and secured to chain, an upper jaw pivotal between a closed clamping position in which it engages the fixed jaw, and an open position in which the web is released from engagement. The upper jaw has an operator which actuated at the entrance end to clamp the jaw on the web material and at the exit end to release the web material.

The heretofore known chain-carried clips have been complex, inefficient and expensive, typically requiring multiple intricate parts. Attempts to eliminate conventional clips in tentering apparatus have not been entirely satisfactory from the standpoints of cost and efficiency. Carr, US. Pat. No. 3,261,903, discloses film stretching apparatus having a chain gripping mechanism wherein each edge of a film is held between two parallel endless chains constructed of special intermeshing links. The mechanism has not been entirely satisfactory in that additional chains with associated sprockets and costly nonconventional links are required.

It has now been found that numerous deficiencies of the prior art are overcome by the present invention which provides a simple efficient gripper for an advancing web of sheet material. The present gripper conveniently and advantageously may be formed of onepiece construction without requiring moving parts. When included as a component of the present assembly which may comprise a conventional endless chain of pivotally interconnected links, the gripper is operable simply by the cyclic traveling action of the chain without detracting from the effective utility thereof.

The present gripper may be used effectively as a component of a variety of apparatus including tenter frames, Hooper machines, and the like.

Generally stated, the present invention provides a gripper for gripping an advancing web of sheet material between a jaw face of the gripper and a jaw face presented by a link in a chain including connected links and pins pivotally interconnecting adjacent links, at least selected ones of said pins each having a hole therethrough, the chain defining a cycling endless loop having at least two arcuate segments and a generally linear segment therebetween. The gripper comprises:

A. a generally U-shaped portion comprising first and second arms connected by a bridging member, the first arm being receivable in one of the holes, and

B. mounting for substantially precluding rotation of the first arm relative to one of the two links directly interconnected by the pin receiving the arm when the first arm is so received and for permitting rotation of the first arm relative to the other of said two links when the first arm is so received, the second arm having a jaw face adapted to cooperate with the jaw of a link spaced from the armreceiving pin to firmly and releasably grip a web therebetween when the first arm is so received and the generally linear segment includes the spaced link and the two directly interconnected links, the arm jaw being angularly displaceable away from the jaw of the spaced link to release the grip when the linear chain segment ceases to include the two directly interconnected links, as occurs during cycling when one of the spaced links and the directly interconnected links is advanced from a linear segment to an arcuate segment of the loop or path.

In the specification and the claims the term web includes almost any type of web material including cotton, wool, synthetic fibers, plastic film, aluminum foil glossy paper, and the like.

Practice of the present invention will become more apparent by referring to the following detailed description taken with the accompanying drawings wherein similar elements are identified by like numerals throughout, and

FIG. 1 is a perspective view which illustrates a gripper embodying the present invention and including an arm having a jaw face;

FIG. 2 is a perspective view illustrating a chain and gripper assembly of the invention;

FIG. 3 is a fragmentary side view illustrating operation of the present gripper in an endless chain arrangement;

FIG. 4 is a perspective view illustrating a tentering operation employing the-present gripper;

FIG. 5 is a plan of view of'a film stretching operation employing the present gripping assembly;

FIGS. 6 and 7 are side and plan views of an embodiment gripper including another mounting means; and

FIGS. 8 and 9 illustrate other grippers embodying this invention.

Referring now to the drawing, FIG. 1 illustrates gripper 10 including a generally U-shaped portion having first arm 12 connected by bridging member 16 to second arm 14 having suitably shaped jaw face 18. The first arm is desirably cylindrical in shape, as shown, for being suitably received in a pin having a cylindrical opening of slightly greater diameter such as a pin of a conventional roller link. The first and second arms preferably project from the bridging member in generally parallel manner each to the other. The gripper includes mounting means provided by third arm 20 and bridge element 22 connecting the first and third arms at ends thereof. Conveniently, the bridge element 22 may be an extension of member 16 which may be generally rectangular in cross section or of other suitable shape. Arm 20 is desirably cylindrical in shape for the purpose described above the reference to the first arm. The third arm is preferably parallel to the first arm. For reasons which will become more apparent below, the jaw face is preferably arcuate and spaced a suitable distance from the plane containing the axes of the first and third arms.

In FIG. 2 there is illustrated assembly 24 including chain 25 formed of a plurality of alternating links 26 and links 28 which appear as plates. Each link is pivotally interconnected to an adjacent link by pins 30. Preferably, for each link or plate 26 there is a corresponding plate 27 and for each link or plate 28 there is a cor responding plate 29. Each link 26 desirably includes a bearing surface provided by the internal surface of sleeve 32 carried by the link in a hole thereof. Each interconnecting pin may include a hole in which a first or third arm of the gripper may be received.

The relationship of the link plates, sleeves and pins is shown in greater detail in the exploded view portion at the left end of the chain in FIG. 2, the various parts there being identified with numerals having the suffix A. (Here and elsewhere alphabetic suffixes are used to identify particular elements where more than one such element is included in the various assemblies.) Plates 26A and 27A are secured about opposite ends of sleeve 32A, as by well known pressure fit means. Plates 28A and 29A are pivotally connected to plates 26A and 27A, respectively, with cylindrically faced holes 35A and 36A of the outer plates coaxial with the sleeve, by means of pin 30A passed coaxially through the sleeve and the holes 35A and 36A. The pin is pivotally carried by at least one of the sleeve and the plate pair 28A and 29A. The arrangement may be a well known roller link wherein the pin is pivotally carried by the sleeve and nonrotatably secured to the plates 28A and 29A as by a pressure fit. Stability may be added by providing head 34A on an end of the pin and, upon assembly, forming a head on the opposite end of the pin as by riveting, flaring or other well known procedures. Due to the pivotal interconnection of the various links, chain 25 may be formed into an endless loop having at least two arcuate segments and a generally linear segment therebetween as shown in FIG. 3.

The chain assembly includes the present gripping device as shown by grippers B and 10B (FIG. 2). Gripper 10B is shown assembled in web gripping position with arm 12B received in the hole through the pin (not shown) within sleeve 32B which connects link plates 26B and 27B. The latter pin pivotally interconnects links 26B and 28B. Jaw 14B is held in web gripping relationship with jaw surface 84 presented by an arcuate recess intermediate the lobes at the opposite ends of link 28C by means of the holding action of arm 20B received in a hole of the other pin (not shown) about which link 28B is pivotally connected to link 26D. The holding action is provided by the moments developed on the gripper 103 about arm 128 by tension stresses externally applied to advance the chain along the substantially linear path defined by the chain segment shown in FIG. 2. It is noted that jaw 14B cooperates with a jaw face presented by a link spaced from the pin which receives first arm 12B.

The mounting means provided by third arm 20B and bridge member or portion 228 substantially precludes rotation of arm 12B relative to link 28B and permits rotation of arm 128 relative to link 26B. The latter link is directly interconnected to link 283 through the pin in which arm 12B is received.

The plane containing the axes of the first and third arms of the chain-mounted gripper is substantially common with the plane containing the axes of the pins in which the arms are received. Webs of any suitable edge thickness may be gripped between corresponding jaws of the gripper and a link. Gripped edges of a web may be, for example, from about 0.01 to about 0.25 inch in thickness. Relatively thin webs are generally gripped with little or no angular displacement of adjacent links while thicker webs are accomodated by sufficient angular displacement of the plane containing the axes of the first and third arms from the plane containing the axes of the pins of the spaced link presenting the jaw surface which cooperates with the jaw of the gripper.

The relationship of a mounted gripper and the chain is further illustrated in the exploded section at the right of FIG. 2. There the broken lines show the alignment of arms 12E and 20E of gripper 10E with the holes of the corresponding pins 30E and the alignment of gripper jaw 14E with one or more of the jaws presented by the arcuate recess edges of links 26E and 27E.

Operation of the present gripper is shown in greater detail in FIG. 3 which illustrates chain assembly 35 including chain 25 formed into an endless loop having arcuate segments 36 and 38 about peripheral portions of sprocket wheels 40 and 42, respectively. The chain loop includes a generally linear segment 44 in an operative run and a generally linear segment 46 in a return run. The chain cyclically travels about the loop in response to rotation of the sprocket wheels which may be driven by any suitable power means (not shown).

Over guides 48 is carried web 50, shown in edge view, which enters and leaves the operative run or zone near stationary points E and L, respectively, which are indicated by arrowheads. Soon after a region of the web enters the operative zone, jaw 14X of gripper 10X having its first and third arms received in holes of the two pins pivotally connecting link 28X to links 26X and 26X, respectively, firmly closes to substantially near the jaw presented by the upper recess edge of link 28X, thus gripping the web between the bite surfaces of the jaws.

Closing and gripping are effected simply by the traveling action of the chain as it successively advances links 28X and 28X from arcuate segment 36 to generally linear segment 44. Link 28X' is spaced from the arm-receiving pin which pivotally interconnects link 28X and intervening link 26X. The resulting closed jaw or gripping position is illustrated by gripper 10Y, carried by pins of link 28Y, now having the bite face of its jaw 14Y substantially nested in the upper recess edge of forwardly spaced link 28Y. A resulting arcuately conforming portion of web 50 is now firmly gripped between the arcuate bite surfaces of the link jaw and gripper jaw.

Cooperating pairs of a link jaw and gripper jaw effectively grip advancing webs through the operative run until the forwardly spaced link presenting the jaw in use arrives at the web release or exit point marking the transition from a linear segment to an arcuate segment of the chain travel path. Release of a grip from the advancing web occurs simply by the traveling action of the chain substantially at the time the forwardly spaced link enters the arcuate segment 38. At such time linear segment 44 ceases to include all three of the gripping spaced link 28Y and the two directly interconnected links 26Y and 28Y, and arm jaw 14Y and the cooperating link jaw are arcuately displaced relatively away from each other. The relatively displaced positions are shown soon after release by the space between jaw 14Z of gripper 102 and the previously operatively engaged upper recess of link 28Z'.

In providing effective close, grip and release action as above described without requiring movable elements or piercing of webs, the present gripper may be conveniently and efficiently used in a variety of gripping operations. An effective use is shown in FIG. 4, wherein web 51 of transparent film is illustrated in a drying operation on a tenter dryer including two generally parallel endless chain and gripper assemblies 35 and 35A of the present invention. The individual operation of assembly 35A is substantially the same as the operation of assembly 35 given in the description above with reference to FIG. 3. Entry sprockets 40 and 40A may be mounted on shaft 52 common thereto and release sprockets 42 and 42A may be mounted on shaft 54. Wet web 51 of shrinkage material to be dried is slightly greater in width that the distance between the opposite inner sides of chains 25 and 25A.

Side margins of the web are advanced onto the chains under the jaws of the open grippers soon before closing thereof. The arrangement may include vertically bowed guide 52 to transversely arch the film thereby facilitating entry of the web margins into gripper engageable alignment. The web is dried by means not shown during its residency in the zone associated with synchronized operative runs 44 and 44A. After drying, the web may be taken up on a roller or passed to other operations as desired. During the period of engagement by the chain assemblies, web shrinkage is substantially prevented by the firm gripping provided by grippers 10 and 10A and the cooperating link jaws.

Another arrangement employing the grippers of the present invention is schematically shown in FIG. 5. In this arrangement, the chain and gripper assemblies 35 and 35A are arranged in diverging relationship for laterally stretching advancing web 57 of thermoplastic film which may be transparent as shown. The web being stretched is guided over heated guide 58, passed through the stretching zone between the chain assemblies 35 and 35A, and thereafter taken up on driven roll 60. In passing through the stretch zone, the web margins are gripped between the gripper jaws and link jaws with the grippers successively closing, gripping and releasing as above described.

The low cost of the present grippers and the efficient simplicity of their operation permit effective lower cost film stretching.

In another embodiment of this invention shown by gripper 110 in FIGS. 6 and 7, the gripper includes a generally U-shaped portion having a first arm 112 connectd by bridging member 116 to second arm 114 having suitably shaped jaw face 118. This gripper includes mounting means provided by tongue 117 received in recess 119 which may be provided radially of the first arm 112 as shown. The tongue is adapted to nonpivotally interconnect the arm to hole-containing pin 130 provided with internal groove 131 for engaging the tongue. The arm and tongue may be formed of unitary construction as by providing the outwardly projecting tongue portion on a generally cylindrical arm body. When assembled with a chain provided with pivot pins as illustrated by pin 130, gripper 110 may be operated substantially as described above with reference to gripper-chain assemblies 24 (FIG. 2) and 35 (FIG. 3). In FIG. 7 pin 130 is shown with part removed for greater clarity in illustrating the gripper assembled therewith.

FIG. 8 illustrates in partial perspective view an embodiment of this invention wherein the third or jaw arm component of the gripper includes projection 19 depending from jaw face 18. One or more depending projections may be included as desired. The illustrated projection is highly suitable for aiding in more firmly gripping a web. For use with a double plate or opposed link chain such as the chain illustrated in FIG. 2 or the like, the projection may be formed of suitable width so that, when the gripper is in gripping engagement with the chain in an operative run thereof, the projection is disposed intermediate opposed links, thereby further flexing and more strongly securing the gripped web.

FIG. 9 illustrates another embodiment of this invention wherein gripper 210 includes a generally U-shaped portion having a first arm 212 connected by slightly flexible or semi-rigid bridging member 216 to second arm 214 having suitable shaped jaw face 218 which appears as an edge in the drawing.

The semi-rigid construction of the bridging member permits minor flexing thereof in the direction indicated by arrows A and B, thereby permitting minor pivoting of second or jaw arm 214 about the axis of first arm 212. The bridging member and jaw are preferably biased in the direction indicated by arrow B, i.e. toward the plane containing the axes of arms 212 and 220. In this embodiment, the gripper is highly suitable for gripping webs of higher thickness in cooperation with a chain with minimum deviation from linearity of link-tolink alignment. Typically, the bridging member is sufficiently rigid so that the angle of pivot of the jaw about the first arm is from about 1 to about 5. When assembled with a chain provided with suitable pivot pins, gripper 210 may be operated substantially as described above with reference to gripper-chain assemblies 24 (FIG. 2) and 35 (FIG. 3).

The present gripper may be formed of any suitable material. Metals, preferably steels, are highly effective. The gripper may be formed using well known forming procedures.

It is understood that the foregoing detailed description is presented merely by way of illustration, and that many variations may be made therein without departing from the spirit or scope of the present invention.

What is claimed is:

l. A grippper for gripping an advancing web of sheet material between a jaw face of the gripper and a jaw face presented by a link in a chain including connected links and pins pivotally interconnecting adjacent links, at least selected ones of said pins each having a hole therethrough, said chain defining a cycling endless loop having at least two arcuate segments and a generally linear segment therebetween, said gripper comprising:

A. a generally U-shaped portion comprising first and second arms connected by a bridging member, said first arm being receivable in one of said holes, and

B. mounting means for substantially precluding rotation of said first arm relative to one of the two links directly interconnected by the pin receiving the arm when the first arm is so received and for permitting rotation of the first arm relative to the other of said two links when the first arm is so received, said second arm having a jaw face adapted to cooperate with the jaw of a link spaced from said armreceiving pin to firmly and releasably grip a web therebetween when the first arm is so received and the generally linear segment includes said spaced link and said two directly interconnected links, said arm jaw being angularly displaceable away from the jaw of said spaced link to release the grip when said linear chain segment ceases to include said two directly interconnected links. 2. The gripper of claim 1 wherein said mounting means includes a third arm receivable in the hole of a pin adjacent the pin in which the first arm is receivable and a bridge member connectng said first and third arms.

3. The gripper of claim 1 wherein said mounting means includes means for non-pivotally interconnecting said first arm with said pin in which said first arm is receivable.

4. The gripper of claim 1 wherein the jaw face thereof is arcuately shaped for nesting in a recessed arcuate edge segment of an elongate link having lobes at opposite pivotally mounted end portions of the link when the elongate link is said spaced link in the chain, said segment being intermediate the lobes and presenting the jaw face of the spaced link.

5. An assembly for gripping an advancing web of sheet material which comprises, in combination:

A. a chain of connected links, said chain adapted to form a cycling endless loop having at least two arcuate segments and a generally linear segment therebetween, at least selected ones of said links each presenting a jaw face, B. pins pivotally interconnecting adjacent links, at least selected ones of said pins each having a hole therethrough, and C. at least one gripper comprising 1. a generally U-shaped portion comprising first and second arms connected by a bridging member, said first arm being received in one of said holes, and

2. mounting means for substantially precluding rotation of said received arm relative to one of the two links directly interconnected by the pin receiving the arm, said means permitting rotation of the received arm relative to the other of said two links, said second arm having a jaw face adapted to cooperate with the jaw of a link spaced from said arm-receiving pin to firmly and releasably grip a web therebetween when the chain is formed in said endless loop and said generally linear segment includes said spaced link and said two directly interconnected links, said arm jaw being angularly displaceable away from the jaw of said spaced link to release the grip when said linear chain segment ceases to include said spaced link and said two directly interconnected links.

6. The assembly of claim 5 wherein said mounting means includes a third arm received in the hole of a pin adjacent the pin receiving the first arm and a bridge member connecting said first and third arms.

7. The assembly of claim 5 wherein said mounting means includes means for non-pivotally interconnecting said first arm with said pin receiving said first arm.

8. The assembly of claim 5 wherein said selected links each presenting a jaw face are generally elongate members each having lobes at opposite pivotally mounted end portions thereof and the jaw face is a recessed arcuate edge segment intermediate the lobes.

9. The gripper of claim 1 wherein said second arm includes a projection depending from said jaw face.

10. The gripper of claim 2 wherein said bridging member is of semi-rigid construction sufficient to permit the jaw arm to slightly pivot about the first arm and the jaw arm is biased toward a plane passing through the first and third arms.

11. The assembly of claim 5 wherein the second arm of said gripper includes a projection depending from said jaw face.

12. The assembly of claim 6 wherein said bridging member connecting said first and third arms is of semirigid construction sufficient to permit the jaw arm to slightly pivot about the first arm and the jaw arm is biased toward a plane passing through the first and third 

1. A grippper for gripping an advancing web of sheet material between a jaw face of the gripper and a jaw face presented by a link in a chain including connected links and pins pivotally interconnecting adjacent links, at least selected ones of said pins each having a hole therethrough, said chain defining a cycling endless loop having at least two arcuate segments and a generally linear segment therebetween, said gripper comprising: A. a generally U-shaped portion comprising first and second arms connected by a bridging member, said first arm being receivable in one of said holes, and B. mounting means for substantially precluding rotation of said first arm relative to one of the two links directly interconnected by the pin receiving the arm when the first arm is so received and for permitting rotation of the first arm relative to the other of said two links when the first arm is so received, said second arm having a jaw face adapted to cooperate with the jaw of a link spaced from said arm-receiving pin to firmly and releasably grip a web therebetween when the first arm is so received and the generally linear segment includes said spaced link and said two directly interconnected links, said arm jaw being angularly displaceable away from the jaw of said spaced link to release the grip when said linear chain segment ceases to include said two directly interconnected links.
 2. The gripper of claim 1 wherein said mounting means includes a third arm receivable in the hole of a pin adjacent the pin in which the first arm is receivable and a bridge member connectng said first and third arms.
 2. mounting means for substantially preCluding rotation of said received arm relative to one of the two links directly interconnected by the pin receiving the arm, said means permitting rotation of the received arm relative to the other of said two links, said second arm having a jaw face adapted to cooperate with the jaw of a link spaced from said arm-receiving pin to firmly and releasably grip a web therebetween when the chain is formed in said endless loop and said generally linear segment includes said spaced link and said two directly interconnected links, said arm jaw being angularly displaceable away from the jaw of said spaced link to release the grip when said linear chain segment ceases to include said spaced link and said two directly interconnected links.
 3. The gripper of claim 1 wherein said mounting means includes means for non-pivotally interconnecting said first arm with said pin in which said first arm is receivable.
 4. The gripper of claim 1 wherein the jaw face thereof is arcuately shaped for nesting in a recessed arcuate edge segment of an elongate link having lobes at opposite pivotally mounted end portions of the link when the elongate link is said spaced link in the chain, said segment being intermediate the lobes and presenting the jaw face of the spaced link.
 5. An assembly for gripping an advancing web of sheet material which comprises, in combination: A. a chain of connected links, said chain adapted to form a cycling endless loop having at least two arcuate segments and a generally linear segment therebetween, at least selected ones of said links each presenting a jaw face, B. pins pivotally interconnecting adjacent links, at least selected ones of said pins each having a hole therethrough, and C. at least one gripper comprising
 6. The assembly of claim 5 wherein said mounting means includes a third arm received in the hole of a pin adjacent the pin receiving the first arm and a bridge member connecting said first and third arms.
 7. The assembly of claim 5 wherein said mounting means includes means for non-pivotally interconnecting said first arm with said pin receiving said first arm.
 8. The assembly of claim 5 wherein said selected links each presenting a jaw face are generally elongate members each having lobes at opposite pivotally mounted end portions thereof and the jaw face is a recessed arcuate edge segment intermediate the lobes.
 9. The gripper of claim 1 wherein said second arm includes a projection depending from said jaw face.
 10. The gripper of claim 2 wherein said bridging member is of semi-rigid construction sufficient to permit the jaw arm to slightly pivot about the first arm and the jaw arm is biased toward a plane passing through the first and third arms.
 11. The assembly of claim 5 wherein the second arm of said gripper includes a projection depending from said jaw face.
 12. The assembly of claim 6 wherein said bridging member connecting said first and third arms is of semi-rigid construction sufficient to permit the jaw arm to slightly pivot about the first arm and the jaw arm is biased toward a plane passing through the first and third arms. 